When saving your work, please leave the default comment but add what you actually mapped, for example "added buildings and a residential road".

Select random task, open it in JOSM, select preferred Imagery.

Once per session, load city splash pads data as new layer. This will create new layer with splash pads as nodes in JOSM. You will later use it when mapping. Make sure you load this layer AFTER loading your first task.

Switch to ottawa-splash-pads.osm layer (click on the 'active' column in Layers window), select the splash pads node in the center and copy all of its tags to clipboard.

Switch back to OSM Data Layer and draw a shape around the splash pad if it already doesn't exist there.

Paste tags from the clipboard to the pool shape. Map and connect any missing OSM elements nearby, such as footways, playgrounds, service ways etc.

Upload changes to OSM. Make sure you do this with OSM layer being active (otherwise JOSM won't allow you to).